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采用流动注射分光光度方法,在碱性条件下使用K3[Fe(CN)6]测定蜂蜜和饮料等食品中的还原糖总量。因葡萄糖和果糖的反应速度存在显著差异,会产生较大的测量误差,从而影响该方法的使用。通过提高反应温度,延长停留时间,可消除葡萄糖和果糖反应速度的差异,并由此建立食品中还原糖总量的流动注射分光光度测定方法。通过一自制的三通流路,将因加热在管道中产生的气泡在线抽出,使反应温度提高到80℃并保持一段时间。试验考察了K3[Fe(CN)6]和NaOH浓度及比例对测定的影响,结果表明,当反应温度80℃、停留时间200s时,以稀释1倍的10mg/mL K3[Fe(CN)6]和100mg/mL NaOH混合溶液(2:1,V/V)为反应试剂,葡萄糖和果糖的反应速度几乎相等,且该方法的灵敏度最高,测量的线性范围为0～10mg/mL(γ>0.999),加标回收率在94.6%～105%之间。利用所建立的方法测定蜂蜜及饮料等食品中的还原糖含量。
Flow injection spectrophotometry was used to determine the total amount of reducing sugars in foods such as honey and beverages using K3 [Fe (CN) 6] under alkaline conditions. Due to the significant differences in the reaction rates of glucose and fructose, large measurement errors can occur, thereby affecting the use of this method. By increasing the reaction temperature and prolonging the residence time, the difference in the reaction speed between glucose and fructose can be eliminated, and a flow injection spectrophotometric method for determining the total amount of reducing sugars in food can be established. Through a self-made three-way flow path, bubbles generated in the pipeline due to heating were drawn online, the reaction temperature was raised to 80 ° C and maintained for a while. The effect of K3 [Fe (CN) 6] and NaOH concentration and ratio on the determination was investigated. The results showed that when the reaction temperature was 80 ℃ and the residence time was 200s, ] And 100mg / mL NaOH (2: 1, V / V) as reaction reagents, the reaction rates of glucose and fructose were nearly equal, and the sensitivity of this method was the highest. The linear range was 0-10mg / mL 0.999). The recoveries of standard addition ranged from 94.6% to 105%. The established method was used to determine the content of reducing sugars in foods such as honey and beverage.